Electrosurgical device

ABSTRACT

A surgical instrument is configured to reduce conductivity between an RF electrosurgical portion and a cutting portion. This reduces improves the efficiency and consistency of the generated RF field, with higher current densities nearest the target tissue, improving the performance of the RF electrosurgical instrument. The conductivity may be reduced using a layer of insulating material, a projecting insulating portion or a cutting portion constructed from an insulating material. Further, by providing a lubricous insulating layer shedding may be reduced, increasing the usable life of the cutting portion.

TECHNICAL FIELD

Embodiments of the present invention described herein relate to anelectrosurgical device, and in particular to an electrosurgical devicewherein a means of reducing conductivity is provided between a firstcutting portion and a pair of electrodes so as to improve theperformance of the device.

Background to the Invention and Prior Art A prior art arrangement, U.S.Pat. No. 7,150,747 B1, describes a surgical device with a blade used tocut tissue mechanically and to coagulate cut tissue. The blade iselectrically conductive and serves as an active electrode in a bipolararrangement with a return electrode. Electrical energy is transferred tothe blade through an electrical connection between the distal region ofthe blade and a second member which has a lumen for receiving the firstmember.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide an improved electrosurgicalinstrument configured to improve the RF field consistency of RFelectrodes which in turn improves the performance of RF coagulation andablation. In a system that provides both bipolar RF functions and acutting action, the end effector has a complex layout which can causecurrent to follow unintended paths from the electrodes to other sectionsof the end effector, such as a rotating cutting edge. It is important toreduce the conductivity of the current path to rotating elements, asthis will improve the consistency of the RF field generated.

Conductivity may be reduced by providing an insulating or isolatingportion between the electrodes and the inner cutting member. This maytake the form of an insulating layer, or an insulating, projectingportion that not only provides insulation itself but ensures separationbetween the return electrode and the inner cutting member. Beneficially,the insulating portion can substantially reduce shedding, where theinner and outer blade contact and microscopic blade fragments can becreated. This minimises the generation of unwanted particulates withinthe surgical site, which could adversely affect surgeon visibility andpatient anatomy.

In view of the above, from one aspect the present invention provides anelectrosurgical end effector, comprising: a rotary shaver arrangement,having a rotatable tubular element with a cutting portion having acutting blade formed therein that when in use is able to cut tissuelocated in an operative cutting direction; an active electrode; a secondtubular element concentrically arranged around the rotatable tubularelement, the second tubular element having a cutting window formed in awall thereof such that the cutting blade of the rotatable tubularelement is located within the window, wherein the outside surface of thesecond tubular element is a return electrode; and an insulating portionprojecting distally from the distal end of the rotatable tubularelement, arranged so as to reduce electrical conductivity between thesecond tubular element and the first cutting portion.

Such an arrangement improves upon the known RF shaver arrangements ofthe prior art by ensuring that the majority of the RF current followsthe intended path from the active electrode to the return electrode.Leakage to the rotatable tubular element is reduced through reducedconductivity, improving the RF efficiency and RF performance of thedevice during ablation and coagulation. When using the coagulation orablation function of the electrosurgical instrument, the inner cuttingmember may be “parked” during which it is stationary (no cutting actionbeing performed). The RF field generated is more consistent over a widerrange of inner blade ‘parking angles’ as the variable position of theinsulated rotatable inner cutting element does not significantly affectthe useful RF field generated at the active electrode. By reducingconductivity to the rotatable tubular element that is in close proximityto the plasma generating electrodes, electrical losses are reduced. Anaxial pre-load force from a hand-piece may be applied to the rotatabletubular element, which forces the cutting portion of the rotatabletubular element into intimate mechanical and electrical contact with thesecond tubular element. In contrast, the radius of the rotatable tubularelement may be separated by a gap from the radius of the second tubularelement. Therefore, placing the insulating portion on the distal end ofthe rotatable tubular element has the greatest impact on reducingconductivity.

In one embodiment, the insulating portion is in contact with the innerdistal end of the second tubular element, acting as the bearing surfacebetween the rotatable tubular element and the second tubular element. Inacting as the bearing surface, the insulating portion reduces the areaof contact between the rotatable tubular element and the second tubularelement. This reduces conductivity, as the only contact between therotatable tubular element and the second tubular element is through aninsulating material. Further, the insulating portion ensures separationbetween the remaining surfaces of the rotatable tubular element and thesecond tubular element, acting to provide an insulating gap. In astandard RF shaver there may be shedding, where small pieces of thecutting blade break off due to friction between the blades. By reducingthe contact area between the rotatable tubular element and the secondtubular element to just the insulating portion, shedding is reduced.This increases the working life of the electrosurgical instrument andreduces the incidence of fragments being left within a patient duringsurgery.

In an embodiment, the insulating portion is one of: a ceramic or apolymer. Providing a non-metal insulating portion results in there beingno metal-on-metal contact during cutting over the distal hemisphereportion of the inner blade, reducing shedding.

Moreover, in a further example the insulating portion is overmoulded ordeposited on the distal end of the first cutting portion.

In one embodiment, the insulating portion is a push-fit insert that isinserted into a suitable receiving geometry, wherein the suitablereceiving geometry is located on one of: the distal end of the firstcutting portion or the inner distal hemisphere of the second tubularelement. A push-fit (or snap-fit) insert allows the insulating portionto be easily attached. Geometries may be chosen to allow differentbenefits, for example the geometry may comprise a hole, a groove or aslot.

In a further embodiment, the material of the insulating portion islubricous. A lubricous material reduces the friction between theinsulating portion and the second tubular element. This can lead to amore consistent cutting action by preventing snags and allowing therotatable tubular element to rotate consistently, which may furtherincrease the efficiency of the electrosurgical end effector by reducingenergy lost to heat. The lubricous material can also substantiallyreduce shedding. Further, this allows closer interaction between thecutting blade and the cutting window of the second tubular element, asless distance is required to prevent the sections catching or snagging.This allows a closer, more accurate tissue cutting action.

Another example describes an electrosurgical instrument, comprising: ahand-piece; one or more user operable buttons on the handpiece thatcontrol the instrument; and an operative shaft, having RF electricalconnections, and drive componentry for an end effector, theelectrosurgical instrument further comprising an electrosurgical endeffector according to any of the above, the rotary shaver arrangementbeing operably connected to the drive componentry to drive the rotaryshaver to operate in use, and the active electrode being connected tothe RF electrical connections.

A further embodiment discloses, an electrosurgical system, comprising:an RF electrosurgical generator; a suction source; and anelectrosurgical instrument according to the above, the arrangement beingsuch that in use the RF electrosurgical generator supplies an RFcoagulation or ablation signal via the RF electrical connections to theactive electrode, to permit tissue coagulation or ablation.

Another aspect of the present invention provides, an electrosurgical endeffector, comprising: a rotary shaver arrangement, having a rotatabletubular element with a cutting portion having a cutting blade formedtherein that when in use is able to cut tissue located in an operativecutting direction; an active electrode; a second tubular elementconcentrically arranged around the rotatable tubular element, the secondtubular element having a cutting window formed in a wall thereof suchthat the cutting blade of the rotatable tubular element is locatedwithin the window, wherein the outside surface of the second tubularelement is a return electrode; and an insulating layer arranged so as toreduce the conductivity between the second tubular element and the firstcutting portion.

This improves upon the known RF shaver arrangements of the prior art byensuring that the majority of the RF current follows the intended pathfrom the active electrode to the return electrode. Leakage to therotatable tubular element is reduced through reduced conductivityimproving the RF efficiency and RF performance of the device duringablation and coagulation. When using the coagulation or ablationfunction of the electrosurgical instrument, the inner cutting member maybe “parked”. The RF field generated is more consistent over a widerrange of inner blade ‘parking angles’ as the variable position of theinsulated rotatable inner cutting element does not significantly affectthe useful RF field generated at the active electrode. By reducingconductivity to the rotatable tubular element that is in close proximityto the plasma generating electrodes, electrical losses are reduced. Anaxial pre-load force from a hand-piece may be applied to the rotatabletubular element, which forces the cutting portion of the rotatabletubular element into intimate mechanical and electrical contact with thesecond tubular element. In contrast, the radius of the rotatable tubularelement may be separated by a gap from the radius of the second tubularelement. Therefore, the insulating layer between the first cuttingportion and the electrodes has the greatest impact on reducingconductivity.

An example describes how the insulating layer is one of: a surfacetreatment, such as an anodized layer; a polymer layer; or a diamond likecarbon, DLC, layer.

Another embodiment describes the material of the insulating layer asbeing lubricous. A lubricous material reduces the friction between theinsulating layer and the inner distal end of the second tubular element,which can lead to a more consistent cutting action by preventing snagsand allowing the rotatable tubular element to rotate consistently. Thelubricous material also prevents or reduces shedding. As there is alower chance of shedding, the rotatable tubular element and the secondtubular element can be located closer together, which provides a moreaccurate cutting action.

A further example describes how the insulating layer is a layer coveringone or more of: the rotatable tubular element; the distal end of therotatable tubular element; the internal radius of the second tubularelement; and/or the external radius of the second tubular element.Providing an insulating layer on the surface of the rotatable tubularelement reduces conductivity. The distal end of the rotatable tubularelement is in closest proximity to the second tubular element thereforeproviding an insulating layer on the distal end can reduce the amount ofinsulating layer or coating material required, whilst still reducingconductivity. A combination of insulating layers on the rotatabletubular element and second tubular element can reduce conductivityfurther.

Another example describes how the rotatable tubular element isconstructed of a non-conductive material, such as ceramic, wherein thesurface of the non-conductive material acts as the insulating layer.Constructing the inner blade of a non-conductive material isolates theblade from the active electrodes. Beneficially, a separate insulatinglayer is not required, reducing manufacturing steps.

Further features and examples will be apparent from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be further described by way ofexample only and with reference to the accompanying drawings, whereinlike reference numerals refer to like parts, and wherein:

FIG. 1 is a schematic diagram of an electrosurgical system including anelectrosurgical instrument according to an embodiment of the presentinvention.

FIG. 2 is a side view of an electrosurgical instrument according to anembodiment of the present invention.

FIG. 3 is view of the tip of FIG. 2, showing the electrosurgical endeffector, wherein the RF function is facing upwards.

FIG. 4 is cross-sectional view of the distal end of the electrosurgicalend effector.

FIGS. 5a and 5b are plan views showing the hollow conductive tube andthe rotatable shaver element.

FIG. 6 is a view of the distal end of the rotating shaver blade, with aninsulating portion.

FIG. 7 is a view of the distal end of the rotating shaver blade, with apush-fit or snap-fit insulating portion.

FIG. 8 is a side view of the rotating shaver blade, with an insulatinglayer.

FIG. 9 is a side view of the rotating shaver blade, with an insulatinglayer on the distal end of the rotating shaver blade.

DESCRIPTION OF THE EMBODIMENTS

Referring to the drawings, FIG. 1 shows electrosurgical apparatusincluding an electrosurgical generator 1 having an output socket 2providing a radio frequency (RF) output, via a connection cord 4, for anelectrosurgical instrument 12. The instrument 12 has a suction tube 14which is connected to a suction source 10. Activation of the generator 1may be performed from the instrument 12 via a handswitch (not shown) onthe instrument 12, or by means of a footswitch unit 5 connectedseparately to the rear of the generator 1 by a footswitch connectioncord 6. In the illustrated embodiment, the footswitch unit 5 has twofootswitches 5 a and 5 b for selecting a coagulation mode or a cuttingor vaporisation (ablation) mode of the generator 1 respectively,although in some embodiments of the electrosurgical instrument 12described herein it is envisaged that only one or other of thecoagulation or ablation modes would be used, with cutting being providedmechanically by way of a rotating tube having a sharpened cut-outportion, described further below. The generator front panel has pushbuttons 7 a and 7 b for respectively setting ablation (cutting) orcoagulation power levels, which are indicated in a display 8. Pushbuttons 9 are provided as an alternative means for selection between theablation (cutting) and coagulation modes.

FIG. 2 shows the electrosurgical instrument 12 forming the basis of anembodiment of the present invention. The instrument 12 includes aproximal handle portion 22, a hollow shaft 24 extending in a distaldirection away from the proximal handle portion, and an end effectorassembly 26 at the distal end of the outer shaft. A power connectioncord 4 connects the instrument to the RF generator 1, whereas tube 14connect the instrument to the suction source 10. The instrument mayfurther be provided with activation buttons (not shown), to allow thesurgeon operator to activate either the mechanical cutting function ofthe end effector, or the electrosurgical functions of the end effector,which in this embodiment typically comprise coagulation or ablation.

FIG. 3 shows an example of the RF side of the electrosurgical endeffector 26. The instrument comprises an active electrode 32, theopening to the primary suction channel 42 and the outer insulatingsheath 34.

FIG. 4 shows the end effector assembly 26 in more detail, comprising anopposite sided shaver arrangement. The end effector comprises a seriesof concentrically arranged tubes, with outer insulating sheath 34containing a hollow conductive tube 36, having at is distal end anopening cut out of one side thereof to act as a cutting window 66. Theedges of the cutting window 66 may be sharpened to provide scissoraction in use against a cutting edge 38 of a cylindrical rotatableshaver element 40. The hollow, conductive tube 36 acts as a returnelectrode and concentrically surrounds a rotatable cylindrical shaverelement 40. By ‘concentrically surrounds’ we mean that the shaverelement 40 is inside and coaxial with the tube 36. The proximal part ofthe tube 36 is covered with the insulating sheath 34. The distal part ofthe tube 36 has the opening which acts as the cutting window 66. Theshaver blade itself is a hollow cylinder of C-shape cross-section at thedistal end, meaning a hollow cylinder which has a segment cut out for aportion of the distal end. The cut out portion is sharpened andserrated, to form the cutting edge 38.

As just noted, at the distal end of the end effector, the shaver blade40 has a sharp cutting edge 38, which may be serrated or shaped intopoints to provide cutting teeth. The hollow shaver blade 40 in usedefines an internal suction lumen 62, which extends along the shaft 24and ultimately connects to the suction source 10. That is, as explainedfurther below, the shaver blade 40 is operative when in use to cuttissue that it is presented against and which is located in a directionto the side of the shaft of the instrument i.e. in a directionorthogonal to the long axis of the instrument. The active electrode 32,operatively faces in the opposite direction to the operative directionof the shaver blade 40, so that in use the user may turn theelectrosurgical instrument 180 degrees to coagulate or ablate tissuethat was cut using the shaver element.

In more detail, to electrosurgically coagulate or ablate tissue, theuser manipulates the instrument 12 such that the active electrode 32 isadjacent to the tissue to be treated, and activates the generator 1 tosupply RF power to the active electrode 32, via the connection cord 4.The RF signal supplied is dependent on whether the active electrode isto simply coagulate (dessicate) tissue, or to ablate the tissue, whereina higher power RF signal is used for tissue ablation than tissuecoagulation. The active electrode 32 and the return electrode 36 act ina bipolar electrode arrangement. The suction lumen 62 is connected tothe suction source 10 such that fluid, tissue fragments, bubbles orother debris in the vicinity of the electrode 32 can be aspirated fromthe surgical site. During operation, rather than entire RF currentflowing along the preferred pathway from the active tip 32 to the hollowconductive tube 36 which acts as a return electrode, there may be acurrent that does not follow the preferred pathway and reduces systemperformance. This problem is exacerbated by the positioning of thesuction lumen 62 and the primary suction channel 42, which, as describedabove, acts to remove debris from the vicinity of both the electrode andthe cutting window.

The line bb indicates the shorter preferential RF tracking path betweenthe active electrode 32 and the return electrode 36. The line cc1indicates the longer, unintended tracking path through the primarysuction channel 42 to the inner blade edge. The line cc2 indicates thelonger, unintended tracking path through the primary suction channel 42to the outer blade—whilst still flowing between the electrodes, thisreduces current density at the point of electrosurgical application. Soas to improve the efficiency and consistency of the generated RF field,it is preferable to reduce current conducted to the rotatable shaverelement (path cc1) or along the longer path to the return electrode(path cc2). Due to the nature of the scissor action and positioning ofthe active electrode, the distal ends of the rotatable shaver element40, the hollow conductive tube 36 and the active RF electrode 32 are inclose proximity. This provides a path for a portion of the RF current topass from the active tip 32, through the primary suction channel 42, tothe rotatable shaver element 40.

So as to improve the performance of the RF function of theelectrosurgical instrument 12, it is desirable to increase theefficiency and consistency of the RF field. This may be achieved byreducing electrical conductivity between the electrodes 32, 36, and therotatable shaver element 40, reducing the current conducted by therotatable shaver element 40. In some instances, this may includeproviding electrical isolation between the electrodes 32, 36, and therotatable shaver element 40 to prevent or reduce the RF current flowingto the rotatable shaver element 40. This results in an increasedproportion of the RF current following the desired path (bb) from theactive electrode 32 to the return electrode 36.

FIG. 5a shows a simplified plan view of the end effector assembly 26including only the hollow conductive tube 36 and the rotatable shaverelement 40. Other parts of the end effector have not been included hereso as to simplify understanding of the concept. As can be seen, thedistal end of the rotatable shaver element 36 may be in contact with orclose proximity to the hollow conductive tube 36 at point 402. So as toprevent a current flowing from the hollow conductive tube 36 to therotatable shaver element 40, FIG. 5b includes an insulating portion 400.This insulating portion 400 is made of an insulating material, such as apolymer or ceramic. As shown in FIG. 6, the insulating portion 400 isattached to and projects distally from the distal end of the rotatableshaver element 40. Alternatively, the insulating portion 400 may beattached to the concave hemispherical surface of the hollow conductivetube 36 and project towards the convex hemispherical distal end of therotatable shaver element. The insulating portion 400 may be over-mouldedor deposited on the surface of the rotatable shaver element 40. Theinsulating portion prevents contact between the distal end of therotatable shaver element 40 and the concave hemispherical distal end ofthe hollow conductive tube 36. Instead, the bearing surface between therotatable shaver element 40 and the hollow conductive tube 36 is theinsulating portion 400. This reduces conductivity, by ensuring that anycontact area between the rotatable shaver element 40 and the hollowconductive tube 36 is an insulating material.

As described earlier, the rotatable shaver element 40 and the hollowconductive tube 36 are in closest proximity at the distal tip of theelectrosurgical instrument 12, so that they may act to provide a scissoraction. Therefore, reducing conductivity at the distal tip will have themost profound effect on overall conductivity between the electrodes andthe rotatable shaver element. In the embodiment of FIG. 5b , theinsulating portion 400 provides a physical insulating separation at thedistal end, as well as resulting in a gap 404 between the remainingsurfaces of the rotatable shaver element 40 and the hollow conductivetube 36. This gap provides a further insulating mechanism. FIG. 7 showsa push-fit (or snap-fit) insert 500 that is attached to a hole 502 (orany suitable receiving geometry such as a groove or slot) in the distalend of the rotatable shaver element 40. This enables easy positioning ofthe push-fit insert 500 on the distal end of the rotatable shaverelement 40. This brings the same advantages as the insulating portion400 described above.

FIG. 8 shows the rotatable shaver element 40 with an insulating layer600 provided over its surface. This is an alternative technique to theuse of a distally projecting insulating portion 400, and reduces theconductivity between the RF electrodes and the rotatable shaver element.

FIG. 9 shows the rotatable shaver element 40 with an insulating layer700 provided on only the distal tip. As described above, due toproximity to the electrodes, providing insulation at the distal end ofthe rotatable shaver element 40 has the greatest effect on reducingconductivity. Beneficially, this requires a smaller portion of therotatable shaver element 40 being covered with an insulating layer,which may reduce the amount of material required, or decrease the timerequired to apply the insulating layer.

Rather than placing the insulating layer on the rotatable shaver element40, it may instead be placed on the hollow conductive tube 36. The layermay be applied to only the internal surface of the hollow conductivetube 36, as this is the closest section of the hollow conductive tube 36to the rotatable shaver element 40 which it surrounds and allows theexternal surface of the hollow conductive tube to act as the returnelectrode. This reduces the amount of insulating material needed.Alternatively, the insulating layer may be provided over the entirehollow conductive tube 36.

The insulating layer 600, 700 may be a diamond like carbon (DLC) orpolymer layer applied to the surface of rotatable shaver element.Alternatively, the insulating layer 600 may be provided by an anodizedsurface.

The layer of insulating material 600, 700 provided over the rotatableshaver element 40, the insulating layer provided over the hollowconductive tube 36, or the insulating portion 400, 500 at the distal endof rotatable shaver element 40 may be a lubricous material. A lubricousmaterial reduces the coefficient of friction, reducing frictional forceswith any material in contact with the lubricous material. In normaloperation, especially where the rotatable shaver element 40 and thehollow conductive tube 36 are metals, the shaver may experienceshedding. Shedding is the generation of particulates due to contact, andthus friction, between the rotatable shaver element and the hollowconductive tube. This can damage the cutting edge 38 of the rotatableshaver element 40, reducing its ability to cut tissue. It may also oralternatively damage the cutting window 36 of the hollow conductivetube. Providing a more effective bearing surface between the rotatableshaver element 40 and the hollow conductive tube 36 by using a lubricousmaterial reduces shedding and thus increases the usable life of theelectrosurgical instrument.

In an alternative example, the rotatable shaver element 40 may beconstructed from a non-conductive material, such as ceramic. This wouldprevent the RF current flowing from the active electrode to therotatable shaver element 40.

The inventors envisage a situation where the above described examplesrelating to insulating layers on multiple parts of the electrosurgicalinstrument and the insulating portion 400 may be combined. This wouldfurther reduce conductivity between the electrodes and the rotatableshaver element. Further, whilst the means of reducing conduction to therotatable tubular element have been described with respect to anopposite sided shaver, the inventors believe that the methods relatingto insulating layers can be applied to a same-sided electrosurgical endeffector. In a same-sided end effector, the RF function is located onthe same side of the end effector as the cutting window, allowingablation/coagulation to be used at the same time as the cutting actionor at the same location without needing to move the electrosurgicalinstrument.

Various modifications whether by way of addition, deletion, orsubstitution of features may be made to above described embodiment toprovide further embodiments, any and all of which are intended to beencompassed by the appended claims.

1. An electrosurgical end effector, comprising: a rotary shaverarrangement, having a rotatable tubular element with a cutting portionhaving a cutting blade formed therein that when in use is able to cuttissue located in an operative cutting direction; an active electrode; asecond tubular element concentrically arranged around the rotatabletubular element, the second tubular element having a cutting windowformed in a wall thereof such that the cutting blade of the rotatabletubular element is located within the window, wherein the outsidesurface of the second tubular element is a return electrode; and aninsulating portion projecting distally from the distal end of therotatable tubular element, arranged so as to reduce conductivity betweenthe second tubular element and the first cutting portion.
 2. Theelectrosurgical end effector according to claim 1, wherein theinsulating portion is in contact with the inner distal end of the secondtubular element, acting as the bearing surface between the rotatabletubular element and the second tubular element.
 3. The electrosurgicalend effector according to claim 1, wherein the insulating portion is oneof: a ceramic; or a polymer.
 4. The electrosurgical end effectoraccording to claim 1, wherein the insulating portion is overmoulded ordeposited on the distal end of the first cutting portion.
 5. Theelectrosurgical end effector according to claim 1, wherein theinsulating portion comprises a push-fit insert that is inserted into asuitable receiving geometry, wherein the suitable receiving geometry islocated on one of: the distal end of the first cutting portion; or theinner distal hemisphere of the second tubular element.
 6. Theelectrosurgical end effector according to claim 1, wherein the materialof the insulating portion is lubricous.
 7. An electrosurgical instrumentcomprising an electrosurgical end effector according to claim 1, theelectrosurgical instrument comprising: a hand-piece; one or more useroperable buttons on the handpiece that control the instrument; and anoperative shaft, having RF electrical connections, and drive componentryfor the end effector, the rotary shaver arrangement being operablyconnected to the drive componentry to drive the rotary shaver to operatein use, and the active electrode being connected to the RF electricalconnections.
 8. An electrosurgical system comprising an electrosurgicalinstrument according to claim 7, and further comprising: an RFelectrosurgical generator; and a suction source; the arrangement beingsuch that in use the RF electrosurgical generator supplies an RFcoagulation or ablation signal via the RF electrical connections to theactive electrode, to permit tissue coagulation or ablation.
 9. Anelectrosurgical end effector, comprising: a rotary shaver arrangement,having a rotatable tubular element with a cutting portion having acutting blade formed therein that when in use is able to cut tissuelocated in an operative cutting direction; an active electrode; a secondtubular element concentrically arranged around the rotatable tubularelement, the second tubular element having a cutting window formed in awall thereof such that the cutting blade of the rotatable tubularelement is located within the window, wherein the outside surface of thesecond tubular element is a return electrode; and an insulating layerarranged so as to reduce the conductivity between the second tubularelement and the first cutting portion.
 10. The electrosurgical endeffector according to claim 9, wherein the insulating layer is one of: asurface treatment, such as an anodized layer; a polymer layer; or adiamond like carbon, DLC, layer.
 11. The electrosurgical end effectoraccording to claim 9, wherein the material of the insulating layer islubricous.
 12. The electrosurgical end effector according to claim 9,wherein the insulating layer is a layer covering one or more of: therotatable tubular element; the distal end of the rotatable tubularelement; the internal radius of the second tubular element; and/or theexternal radius of the second tubular element.
 13. The electrosurgicalend effector according to claim 9 wherein the rotatable tubular elementis constructed of a non-conductive material, such as ceramic, whereinthe surface of the non-conductive material acts as the insulating layer.14. An electrosurgical instrument comprising an electrosurgical endeffector according to claim 9, and further comprising: a hand-piece; oneor more user operable buttons on the handpiece that control theinstrument; and an operative shaft, having RF electrical connections,and drive componentry for an end effector, the rotary shaver arrangementbeing operably connected to the drive componentry to drive the rotaryshaver to operate in use, and the active electrode being connected tothe RF electrical connections.
 15. An electrosurgical system comprisingan electrosurgical end effector according to claim 9, and furthercomprising: an RF electrosurgical generator; and a suction source; thearrangement being such that in use the RF electrosurgical generatorsupplies an RF coagulation or ablation signal via the RF electricalconnections to the active electrode, to permit tissue coagulation orablation.
 16. An electrosurgical system comprising an electrosurgicalinstrument according to claim 14, and further comprising: an RFelectrosurgical generator; and a suction source; the arrangement beingsuch that in use the RF electrosurgical generator supplies an RFcoagulation or ablation signal via the RF electrical connections to theactive electrode, to permit tissue coagulation or ablation.